The FEECO Innovation Center and Satisfactory Alumina

At FEECO Innovation Center, test batches of alumina are evaluated to ascertain its suitability for specific uses. If viable, the material is processed into an after-firing ceramic material to fulfill application specifications.

Alumina can add matteness to glazes at very low levels (less than 5%) by decreasing shrinkage due to kaolin content and stabilizing glaze melts.

Abrasive Resistance

Acid resistance of cementitious materials depends upon their type and concentration of acidic media as well as the testing methodology employed to assess it.

Recent developments have witnessed dramatic advances in the rheological behavior, setting properties, and structural characteristics of alumina-based binders. This may be attributable to advances in understanding their chemical and physical formation processes as well as new types of low carbon activators with lower environmental footprints than traditional phenolic concrete binders.

Acid resistance is a critical property of AABs. However, it should be remembered that acid resistance alone does not determine its performance; other factors, including type and concentration of acids used as well as surface condition of aggregates and the alumina itself all influence performance.

Bauxite mines and refineries tend to be located in tropical climates, where parasites, infectious diseases (such as malaria and tuberculosis) and dangerous/venomous animals pose potential threats of disease. Workplace safety issues at these locations include noise, vibration, ergonomics trauma and caustic soda splashes on skin or eyes as well as noise monitoring to assess respiratory, dermatological and cardiovascular health issues.

Bauxite ore contains trace amounts of uranium (238U), thorium (232Th), and potassium (40K), all of which transfer almost entirely into the solid residue stream during refining (Bayer process materials before precipitation, mud residue, sand residue and alumina). Positional and personal monitoring at Pinjarra Refinery in Western Australia have revealed that radiation doses associated with handling these residues remain below background radiation exposure limits and therefore should not pose an overly risky exposure risk to personnel handling them.

Acid Resistance

Alumina industry employs chemical processing in order to obtain pure aluminium hydroxide for smelting. Bauxite serves as its principal raw material and contains impurities which can be removed through physical beneficiation; however, this doesn’t always produce desired quality alumina and requires further chemicals as refiners improve its properties; its final products find use in industrial applications such as refractories and ceramics. Alumina boasts high density with nonporous surface that resists liquid penetration as well as gas penetration from outside sources; hence making a perfect candidate for use as the principal raw material for manufacturing this industry.

Density of Alumina relates directly to its porosity, determined by oxygen ions present. Alumina with less oxygen ions has greater density. Alumina also exhibits good acid resistance due to its reaction with hydroxide ions; due to this property it serves as the main component in blasting materials and refractory bricks, as well as being essential in creating medical grade ceramics.

To increase alumina’s acid resistance, it can be treated with various acids to alter its surface. These treatments alter both morphology and chemical composition of ceramic particles; recently in one study samples of medical-grade alumina and zirconia were etched using three combinations of acids; scanning electron microscopy observed their appearance while EDS mapping provided insight into their chemical makeup.

Acid etching can be a dangerous operation, so every precaution must be taken to protect workers from exposure to hazardous chemicals. These measures include wearing protective clothing and goggles. Routine mercury testing at alumina refineries isn’t conducted due to mercury levels being well below ACGIH occupational exposure limit of 20 mg/g creatinine in workers’ urine samples.

Density

Alumina ceramic materials are highly suitable for extreme service environments due to their resistance against abrasion, corrosion, heat and erosion. Alumina technical ceramics also make excellent thermal insulators with electrical properties that translate into high dielectric values (for converting DC frequencies to GHz frequencies). Furthermore, Alumina ceramics have self-lubricating properties and dimensionally stability making them excellent choices in high service environments.

Fine-grain alumina (Al2O3) boasts excellent formability, making it suitable for injection molding, dry pressing, isostatic pressing, hot pressing, slip casting and slip forming applications. Available with purity levels from 94% suitable for metalizing to 99.8% for high temperature applications it offers versatility when creating products of all sorts.

Zirconia toughened alumina compounds are highly effective ceramic materials for extreme environments, including temperature resistance, wear resistance, abrasion resistance and chemical inertness. Used in manufacturing applications for pump liners, valve components, sleeves pistons plugs etc, their high fracture toughness makes alumina ceramics an excellent choice for precision machining processes.

Alumina ingot and powder forms can be machined using traditional green and biscuit machining methods, while its full densification requires the sintering process, which results in significant shrinkage that requires diamond tools for precision machining. Alumina is often used as an economical alternative to steel in grinding and cutting operations due to its low coefficient of friction and durability; this lowers operational costs significantly.

Alumina can be quenched by many liquids, including water, alcohols, acids and glycerine – with the latter having the highest boiling and decomposition points of all. Pure alumina’s low solubility also contributes to its resistance against chemical corrosion as it can withstand strong acids and alkalis but not water.

Heat Resistance

High hardness alumina is a critical property in its manufacturing processes, since its strength makes them relatively energy efficient. Alumina’s hardness results from strong bonding between its tightly packed crystalline structures that give strength while resisting breakage. Thus making it one of the world’s hardest materials; three times harder than stainless steel and four times as hard as silicon carbide respectively.

Aluminum producers face one of their greatest challenges today in developing inert anodes for industrial alumina reduction cells. Copper anodes were initially seen as suitable alternatives; however, their rapid dissolving in electrolyte compromised fresh aluminum produced and quickly polluted it further – carbon anodes remain the only viable and practical solutions available to them.

An additional challenge facing aluminum production lies in energy reduction. At present, aluminum industries consume 13-11 kWh/kg Al in production – double what should be necessary. This is mostly due to coal-fired power plants providing most of this energy. Decreased energy usage will have positive environmental and efficiency benefits that will contribute to increased aluminum production efficiency.

Alumina plays an essential role in helping capture hydrogen fluoride gas produced in anode cells. Alumina powder absorbs this gas while simultaneously trapping fluoride condensates, such as particulate sodium tetrafluoroaluminate (NaAlF4) particles, that then return back to fume treatment plants before returning back into production cells for smelting operations. Reducing HF gas emissions significantly contributes to safety at alumina refineries and mines alike.

Hardness

Alumina’s high hardness, superior strength and resistance to impact and abrasion make it an ideal material for producing industrial products and machines. Furthermore, its heatproof qualities help withstand high temperatures commonly found in the refractory industry – where it is used in processes like petrochemical processing, waste incineration, cement production and iron and steelmaking.

Mohs hardness of 9 puts Alumina second only to diamond in terms of hardness. Able to withstand steel ball abrasion as well as impact from small arms fire and medium caliber cannons, its hardness and durability also makes it suitable as protective armour material.

Alumina stands out from other materials with its hardness, chemical inertness, and resistance to acid attack by being resistant to orthophosphoric and hydrofluoric acids as well as many others. Furthermore, its electrical insulating qualities and purity – up to 99% – make it suitable for electronic substrates and insulators.

ZTA (zirconia toughened alumina) is an alloy created by mixing yttria-stabilised zirconia (YSZ) into an alumina matrix to optimise wear properties of this material. By increasing flexural strength, fracture toughness, abrasive resistance and age resistance YSZ makes ZTA less prone to ageing over time.

ZTA ceramics’ abrasive resistance is directly tied to their grain structure and particle distribution; for optimal performance, this should consist of finer grains with dense structures that evenly distribute particle sizes. Bending capacity also depends heavily on grain structure; tempers play an essential part when optimizing bendability since they determine bond strength between individual grains.